The problems of residual house spraying for anopheline control and the development of resistance in mosquitoes to residual insecticides are reviewed and discussed. The needs for the development and implementation of control measures against pre-imaginal stages of mosquitoes in their breeding sources are brought in focus. To make further progress in the area of malaria eradication and anopheline control, it will be necessary to foster and utilize control measures developed against the immature stages. This approach becomes an indispensable tool in view of the exophilic and exophagic behavior of anopheline mosquitoes and their tolerance to standard residual materials and the availability of a very limited number of substitute materials for use as residual adulticides.

To obtain maximum benefit from the use of pre-imagicides, it is essential to implement various suppressive measures in a “harmonized” and “integrated” manner. The role of biotic control agents should be fully understood and their potential effects on mosquito populations maximized. The outlook for integrating the pre-imagicides with fish and game species seems rather bright. Methods and timing of applications, use of selective nonpersistent materials and formulations, and frequency of treatments are some of the parameters that can be manipulated for achieving maximum control with minimum effect on fish and game species. Acute and chronic effects of any large-scale control program on specific game and fish species must be studied adequately.

However, the use of pre-imagicides in aquatic habitats poses problems with regard to the nontarget arthropod fauna. This fauna, closely related to mosquitoes, suffers the most from chemicals introduced into the aquatic ecosystem. Examples of the interaction of Dursban^® (O,O-diethyl O-3,5,6-trichloro-2-pyridyl phosphorothioate), an organophosphorus larvicide and some selected species of aquatic insects are discussed. Crustaceans belonging to the Cladocera and naiads of baetid mayflies were the most susceptible organisms to this chemical. It is very likely that some organophosphate insecticides at mosquito larvicidal rates will adversely affect the populations of these 2 groups of arthropods. Other groups of aquatic insects show various degrees of susceptibility to various larvicides. Recovery and reestablishment of these organisms in treated areas will depend on the frequency of applications, type of material used, and the extent of the breeding source treated. Hazards to game and other nontarget organisms will be greater if insecticidal treatments are made frequently and applied over large areas.

In addition to a discussion of mosquito larvicides and their use in an integrated control technology, other measures and techniques for the control of pre-imaginal mosquitoes are discussed. Emphasis is placed on the development of measures which will interfere with development and morphogenesis of pre-imaginal mosquitoes. The potential efficacy and problems associated with low-volume and ultra low volume applications, slow release formulations, and other novel techniques are presented.

For further development and implementation of pre-imagicidal measures for the suppression of anopheline and other mosquitoes, research needs are enumerated. In contrast to research on adult anopheline control, present research programs dealing with the control of preimaginal stages are meager. To implement preimagicidal measures, research on the development of these measures must be expanded materially.